The present invention relates to a coating agent useful for forming a glassy film on a substrate, to a coating method using the same, and to a bottle coated with the coating agent.
Further, the present invention also relates to a coating system useful for forming a glassy film on a substrate.
The sol-gel process using as a starting material a solution of an organic or inorganic compound of a metal such as a silicon alkoxide has conventionally been known as one of the methods for manufacturing glass. In this process, the hydrolysis and condensation polymerization reaction of the compound are carried out in the solution to make the solution into a sol in which fine metallic oxide or hydroxide particles are dispersed. The sol is then made into a gel by allowing the reaction to further proceed; the gel is dried to give a porous gel; and this porous gel is heated to produce glass or ceramic. This process is also known as a method for imparting additional values to substrates to manufacture functional glass that can be used as anti-reflecting films or color filters for cathode ray tubes.
A method for forming colored coatings on such objects as glass bottles by employing this sol-gel process has already been disclosed in Japanese Patent Laid-Open Publication No. 178623/1993. According to this publication, a colored filter is obtained by dispersing fine particles of a pigment in a silica gel film by the sol-gel process. In this method, the film to be colored is a silica gel film. Since a silica gel film tends to be cracked when dried, it is difficult to form a film with a thickness in the order of several microns. This method therefore seems to have such a problem that it is necessary to make the concentration of fine organic pigment particles extremely high in order to obtain a deeply colored silica gel film.
J. Non-cryst. Solid, 100, 490 (1988) discloses organic-inorganic composites obtained by directly combining organic compounds with inorganic components. The temperature required to calcine the composites is as high as 650xc2x0 C. It is unfavorable from the economical point of view to reheat once-shaped glassware, substrate, to such a high temperature. There is therefore a demand for a composite that hardens at a lower temperature in a shorter time.
Japanese Patent Laid-Open Publication No. 137737/1990 is directed to the production of organic-inorganic hybrid glass, and discloses a method for manufacturing organic-inorganic hybrid glass that hardens at low temperatures. Organic siloxanes having highly organic nature are used in this method, so that their affinities for glass surfaces seem to be low.
A method using organic silicon compounds is also disclosed in Japanese Patent Laid-Open Publication No. 315849/1995. The main component of organic groups in the organic silicon compounds is phenyl group. Therefore, although coatings containing these organic silicon compounds are excellent in abrasion resistance, it cannot be expected that the coatings harden rapidly.
Mat. Res. Soc. Symp. Proc., Vol. 180, 767 (1990) and Vol. 180, 995 (1990) report organic-inorganic hybrid materials which harden when irradiated with ultraviolet light. However, these literatures are quite silent on the dispersibility of fine particles; this information is necessary for the formation of colored films by the use of fine particles of organic pigments.
Published Japanese Translation No. 501694/1992 of PCT international publication for patent application describes glass containers coated with colored layers. These colored layers are made from organic materials, and, in addition, their thicknesses are as large as 10 micrometers or more. It is therefore difficult to re-use such glass containers as resources. Moreover, cullet of poor quality can only be obtained when these glass containers are crushed.
Accordingly, there has conventionally been demanded a colored organic-inorganic hybrid material which can give a thin film with its thickness in the order of microns being well controlled, in which an organic pigment is dispersed at high dispersibility, which hardens rapidly at low temperatures, which shows high adhesion to glass, and which can make it easy to re-use coated glass as resources; and a glassy-film-coating method using this hybrid material.
 less than Summary greater than 
A glassy-film-forming coating agent of the present invention comprises compounds represented by the following general formulae (1), (2) and (3):
R1pSi(OR2)4xe2x88x92pxe2x80x83xe2x80x83(1)
R2(OSi(OR2)2)qOR2xe2x80x83xe2x80x83(2)
M(OR3)rxe2x80x83xe2x80x83(3)
wherein
R1 is a polymerizable organic group,
R2 is an alkyl group having not more than 4 carbon atoms,
R3 is an alkyl group having not more than 6 carbon atoms,
p is an integer of 1 to 3,
q is an integer of 1 to 10,
M is a trivalent or tetravalent metal ion, and
r is an integer of 3 or 4 corresponding to the valence of M,
provided that, when one of the compounds contains two or more R1s, R2s or R3s, they may be the same or different.
A glassy-film-coating method of the present invention comprising:
applying, to a substrate, a coating agent which comprises compounds represented by the following general formulae (1), (2) and (3):
R1pSi(OR2)4xe2x88x92pxe2x80x83xe2x80x83(1)
R2(OSi(OR2)2)qOR2xe2x80x83xe2x80x83(2)
M(OR3)rxe2x80x83xe2x80x83(3)
wherein
R1 is a polymerizable organic group,
R2 is an alkyl group having not more than 4 carbon atoms,
R3 is an alkyl group having not more than 6 carbon atoms,
p is an integer of 1 to 3,
q is an integer of 1 to 10,
M is a trivalent or tetravalent metal ion, and
r is an integer of 3 or 4 corresponding to the valence of M,
provided that, when one of the compounds contains two or more R1s, R2s or R3s, they may be the same or different, and
subjecting the coating agent applied to the substrate to irradiation and/or heat treatment.
A coated bottle of the present invention is obtained by applying, to a bottle, substrate, a coating agent which comprises compounds represented by the following general formulae (1), (2) and (3):
R1pSi(OR2)4xe2x88x92pxe2x80x83xe2x80x83(1)
R2(OSi(OR2)2)qOR2xe2x80x83xe2x80x83(2)
M(OR3)rxe2x80x83xe2x80x83(3)
wherein
R1 is a polymerizable organic group,
R2 is an alkyl group having not more than 4 carbon atoms,
R3 is an alkyl group having not more than 6 carbon atoms,
p is an integer of 1 to 3,
q is an integer of 1 to 10,
M is a trivalent or tetravalent metal ion, and
r is an integer of 3 or 4 corresponding to the valence of M,
provided that, when one of the compounds contains two or more R1s, R2s or R3s, they may be the same or different, and
subjecting the coating agent applied to the bottle to irradiation and/or heat treatment.
A glassy-film-coating system of the present invention comprises the following units:
(a) a coater for applying, to a substrate, a coating agent comprising compounds represented by the following general formulae (1), (2) and (3):
R1pSi(OR2)4xe2x88x92pxe2x80x83xe2x80x83(1)
R2(OSi(OR2)2)qOR2xe2x80x83xe2x80x83(2)
M(OR3)rxe2x80x83xe2x80x83(3)
wherein
R1 is a polymerizable organic group,
R2 is an alkyl group having not more than 4 carbon atoms,
R3 is an alkyl group having not more than 6 carbon atoms,
p is an integer of 1 to 3,
q is an integer of 1 to 10,
M is a trivalent or tetravalent metal ion, and
r is an integer of 3 or 4 corresponding to the valence of M,
provided that, when one of the compounds contains two or more R1s, R2s or R3s, they may be the same or different, and
(b) a coating-hardening unit for irradiating and/or heating the coating agent applied to the substrate.
 less than Effects greater than 
The coating agent of the present invention can give a thin film having sufficiently high flexibility with its thickness in the order or microns being well controlled. Moreover, in the case where an organic pigment is incorporated into the coating agent, it shows high dispersibility. In addition, the coating agent gives a vitreous film that hardens rapidly at low temperatures.